Boverisuchus

History

The type species Boverisuchus magnifrons was first named by paleontologist Oskar Kuhn in 1938, from the Lutetian of Germany alongside Weigeltisuchus geiseltalensis. Most paleontologists have considered both species to represent junior synonyms of the type species of Pristichampsus, P. rollinatii. Following a revision of the genus Pristichampsus by Brochu (2013), P. rollinati was found to be based on insufficiently diagnostic material and therefore is a nomen dubium while Boverisuchus was reinstated as a valid genus. Brochu (2013) also assigned Crocodylus vorax, which has been referred to as Pristichampsus vorax since Langston (1975), as the second species of Boverisuchus. According to Brochu (2013), material from the middle Eocene of Italy and Texas may represent another yet unnamed species. The two Asian species of Planocrania were found to be most closely related to Boverisuchus using a phylogenetic analysis. The name Planocraniidae was reinstated to contain these genera and replace Pristichampsidae.

Phylogeny

Phylogenetic analyses based purely on morphological data have generally placed Planocraniidae in a basal position within the crocodilian crown group. Some of these analyses have found that planocraniids lie just outside Brevirostres, a group that includes alligators, caimans, and crocodiles but not gharials. However, molecular studies using DNA sequencing have found the group Brevirostres to be invalid upon finding that crocodiles and gavialids are more closely related than alligators.

A 2018 tip dating study by Lee & Yates using both molecular, morphological and stratigraphic data instead recovered the planocraniids outside crown group Crocodylia. Below is a cladogram from that study:

In 2021, Rio & Mannion conducted a new phylogenetic study using a heavily modified morphological data set, and also noted the lack of consensus and difficulty in placing Planocraniidae. In their study, they recovered Planocraniidae within Crocodylia, as the sister group to Longirostres, as shown in the cladogram below:

Description and habits

Based on other planocraniids, Boverisuchus is assumed to have had heavily armoured skin, and long limbs suggesting a cursorial (i.e. running) habitus. It also had hoof-like toes, suggesting that it lived more on land than in the water, and that it therefore probably hunted terrestrial mammals. The teeth of Boverisuchus were ziphodont; i.e., laterally compressed, sharp, and with serrated edges (characteristic of terrestrial crocodyliforms that are unable to dispatch their prey by drowning them). Due to their similarity to those of certain theropod dinosaurs they were initially mistaken for theropod teeth, leading paleontologists to believe that some non-avian dinosaurs survived the Cretaceous–Paleogene extinction event.

Some material referred to Pristichampsus rollinatii shows further features adapting the animal to this lifestyle. The tail was more reminiscent of a dinosaur's, being round in cross-section and lacking the osteoderm crest observed in extant crocodile species. It would also have been capable of galloping.

References

References

1. (6 September 2021). "Phylogenetic analysis of a new morphological dataset elucidates the evolutionary history of Crocodylia and resolves the long-standing gharial problem". [[PeerJ]].
2. (2013). "Phylogenetic relationships of Palaeogene ziphodont eusuchians and the status of ''Pristichampsus'' Gervais, 1853". Earth and Environmental Science Transactions of the Royal Society of Edinburgh.
3. (27 June 2018). "Tip-dating and homoplasy: reconciling the shallow molecular divergences of modern gharials with their long fossil record". Proceedings of the Royal Society B: Biological Sciences.
4. (2020). "Vertebrae-Based Body Length Estimation in Crocodylians and Its Implication for Sexual Maturity and the Maximum Sizes". Integrative Organismal Biology.
5. (2020). "A systematic review of the giant alligatoroid ''Deinosuchus'' from the Campanian of North America and its implications for the relationships at the root of Crocodylia". [[Journal of Vertebrate Paleontology]].
6. Blanco, A.. (2021). "Importance of the postcranial skeleton in eusuchian phylogeny: Reassessing the systematics of allodaposuchid crocodylians". [[PLoS ONE]].
7. (2003). "True and false gharials: A nuclear gene phylogeny of crocodylia". Systematic Biology.
8. (2008). "The rapid accumulation of consistent molecular support for intergeneric crocodylian relationships". [[Molecular Phylogenetics and Evolution]].
9. Erickson, G. M.. (2012). "Insights into the ecology and evolutionary success of crocodilians revealed through bite-force and tooth-pressure experimentation". PLOS ONE.
10. Michael S. Y. Lee. (27 June 2018). "Tip-dating and homoplasy: reconciling the shallow molecular divergences of modern gharials with their long fossil". [[Proceedings of the Royal Society B]].
11. (2021-04-27). "Paleogenomics illuminates the evolutionary history of the extinct Holocene "horned" crocodile of Madagascar, Voay robustus". Communications Biology.
12. (1999). "The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals". Marshall Editions.
13. Rossmann T. 2000. Studies on Cenozoic crocodiles: 5. Biomechanical investigation on the postcranial skeleton of the Palaeogene crocodile ''Pristichampsus rollinatii'' (Eusuchia: Pristichampsidae). ''Neues Jahrbuch fuer Geologie und Paläontologie Abh.'' '''217''' (3) 289-300.